html, body{margin:0; padding:0; height:100%;}
#contenedor{width:100%; background:#FFF; min-height:100%; position:relative;}
.CF_seccion{background:#ededed; border-bottom:1px solid#999; padding:.5em; box-sizing:border-box;}
.caja_centro{text-align:center; margin:0; padding:0;}
.volver{text-align:right; padding:.4em; width:90%; margin:0 auto;}

#cabecera{margin:0;padding:0;}

#cuerpo{
border:2px solid #000;
background:-webkit-linear-gradient(#ddd, #fff);
background:-moz-linear-gradient(#ddd, #fff);
background:-o-linear-gradient(#ddd, #fff);
background:linear-gradient(#ddd, #fff);}

#cierre{position:absolute; bottom:0; width:100%;}

.contenedor_doc {
   position: relative;
   overflow: hidden;
   background-color: #FFF;
   width: 100%;
}
.contenedor_doc iframe
 {
    position: absolute;
    display: block;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
}